SSM Mailout Ahead Of Schedule

More than 4 million delivered

If you haven't got your same sex marriage survey in the post yet, don't panic because it's on the way.

More than four million forms have already been delivered and a million more are tipped to be in people's mailboxes today, with a senate inquiry told the whole process is pretty much ahead of schedule.

"We're slightly ahead of our schedule for dispatch of remaining forms, so that all means we're in very good shapes to all eligible Australians by September 25,"Deputy Australian StatisticianJonathon Palmersaid.

If you're one of the 120,000 silent voters, then you can expect to have your survey form sent out to you next week, while those who are living overseas won't actually get an online code until September 25.

The result is going to be kept under wraps until it's announced.

"We'll keep the statistics under strict embargo and very few people - I'm talking less than a handful - will know the result before it's published."